1. Field of the Invention
The present invention relates to a digital broadcast receiving apparatus.
2. Description of the Related Arts
A digital broadcast wave includes broadcast data of a physical channel which are assigned to each of frequency band respectively, and the broadcast data of each physical channel includes broadcast data of a plurality of sub channels. Further, the digital broadcast wave includes the PSIP (Program System Information Program), and a digital broadcast receiving apparatus which generates a channel map data based on the PSIP and stores the channel map data is known. (For example, see Patent Document 1.)
Moreover, there are sub channels which can be viewed for free and sub channels in which fees are charged for viewing. Usually, a video data and an audio data of the sub channels in which fees are charged are encoded (hereinafter, scrambled) so that only person who paid the fee can view the sub channels. There is known a digital broadcast receiving apparatus that generates and stores a channel schedule which only consists of not-scrambled sub channels (for example, Patent Document 2) and a digital broadcast receiving apparatus which stores an information relating to whether the sub channels are scrambled or not-scrambled for each of the sub channels (for example, Patent Document 3).
Patent Document 1: JP-Tokuhyou-2003-533060
Patent Document 2: JP-Tokukaihei-11-177956
Patent Document 3: JP-Tokukai-2005-151333
However, although the channel map data is once generated, updating of the channel map data is needed because the scrambling information differs according to days and time slots. On the one hand, it is complicated to scan all of the physical channels for every update, and on the other hand, by merely updating the physical channels which only have the not-scrambled sub channels, the physical channels which scrambling is released cannot be updated.